1. Field of the Invention The present invention relates to a method of maintaining security in a common output means such as a print server and to a system for maintaining security for realizing the method of maintaining security. More specifically, the invention relates to a method of maintaining security which guarantees security in the common output means such as printer means represented by a network printer that is used in common by clients such as a plurality of personal computers, as well as to a system for maintaining security adapted to such a method.
In an environment where there exist many clients and at least one or more print servers, it is a tendency that less and less printers are now locally connected to clients but, instead, one or more network printers are used in common via a network such as LAN (local area network). The present invention is adapted to a constitution having a print server that is used in common being connected to the LAN but is in no way limited thereto only.
2. Description of the Related Art
In an apparatus including a printer as an output means (i.e., a printer and its peripheral units, as usually called printer unit), it is not desired to provide many printer units despite there are many people who use the printer unit, since provision of many printer units decreases space efficiency in an office.
Moreover, improved printing performance is accompanied by an increase in the cost of the printer unit, and provision of such expensive printer units in great numbers must be avoided from the standpoint of installation cost, as well.
In general, inquiries about the print jobs and the preferential process input by the clients can be carried out by a management function of a common internal spool for holding print job of a print server or a file server (inclusive of processing of the server acted by the client). In recent years, furthermore, there can be contrived a LAN environment which carries out the operation in a simplified manner by omitting dedicated server systems but using a network printer that has a large capacity of memory for the internal spool. In this case, the print jobs thrown into the internal spool of the network printer by the individual clients are queued in the spool and are then output usually in the form of first-in, first-out (FIFO).
Because of such backgrounds, therefore, one or more common print servers are now used under most LAN environments. FIG. 1 is a diagram illustrating the constitution of a conventional print server. A print server 505 is generally constituted by a printer unit 503 and a work-station 502.
The work-station 502 is connected to a network 504, and the printer unit 503 is connected to the work-station 502. In this constitution, the print job is received by the work-station 505 via the network 504.
The received print jobs are determined for their order of printing by way of control by the work-station 502 according to a predetermined rule such as order of decreasing priorities, order of reception, etc., and are printed by the printer unit 503.
The print jobs are designated by so-called clients 500 to 501 connected to the same network 504. Being controlled by the work-station 502, the printer unit 503 is used in common by the plurality of clients 500 and 501.
It is now presumed that a user A throws in a print job "a" through the client 500 that must be kept secret from other persons. Then, another user B throws in a print job "b" through the client 501.
Under this condition, if the user B comes over to the print server 505 earlier than the user A while the print job "a" thrown in by the user A is being printed, then, the output result of the print job "a" which the user A wishes to keep secret may be watched by the user B, i.e., the printed result of the printer unit may be watched by the user B. Besides, there is a likelihood that the printed result may be obtained by the user B.
In the conventional constitution of using the print server in common, therefore, the user A must go to the print server 505 immediately after he has thrown in the print job if he wishes to keep it secret. Despite of rushing to the print server 505, however, the printing may have already been executed or, conversely, the print job that is thrown in may have been waiting for a long period of time until other print jobs are done.
If locally dedicated printer units are made available to only limited persons, on the other hand, the merit of saving the cost by using a printer unit in common eliminating the individual printer units, is not sufficiently exerted and, besides, the problem of unfairness takes place in that the chances for outputting confidential print jobs are restricted only to limited number of persons.
Moreover, even when a printer unit dedicatedly used for security output only is provided, there develops the same problem as the one described above, in the case where it is used in common by more than one persons.
Furthermore, even when the printer unit is equipped with locked stackers, it will be difficult to assign one such locked stacker for each person who wishes to use the printer unit without arousing the problem of unfairness. If a plurality of users are assigned to one stacker in order to increase the number of persons who use the printer unit, the secrecy will be easily broken depending upon the manner of using the keys.
In an environment in which the printer unit is used in common as described above, it is difficult to easily output the prints that should be kept secret from other persons. It has therefore been desired to provide a method of maintaining security without losing the merit of using the printer unit in common.